Remote convenience systems are known in the art. Such remote convenience systems permit remote control of certain functions. One type of a remote convenience system is for remotely controlling vehicle functions. Other example types of remote convenience systems include garage door opener systems and entry light activation systems.
Examples of remotely controlled functions for vehicles include locking and unlocking of one or more vehicle doors. A remote convenience vehicle system that permits remote locking and unlocking functions is commonly referred to as a remote keyless entry ("RKE") system.
Such remote convenience vehicle systems may provide for control of other vehicle functions. For example, a remote vehicle locator function may be provided. The vehicle locator function causes the vehicle horn to emit a horn chirp and/or the headlights of the vehicle to flash. This allows a person to quickly locate their car within a crowded parking lot.
Known remote convenience vehicle systems include a receiver/controller mounted in an associated vehicle and at least one portable, hand-held transmitter located remote from the receiver. The receiver/controller has a memory that stores one or more security codes, each of which is associated with a transmitter that is authorized to cooperate with the receiver/controller mounted in the vehicle. Also, the receiver/controller is operatively connected to one or more vehicle systems that perform the functions that are remotely requested.
Each transmitter is provided with one or more manually actuatable switches. Each transmitter switch is associated with a remote control vehicle function to be performed. The transmitter includes circuitry that responds to the actuation of each switch to transmit a message in the form of a digital signal. The transmitted digital signal also includes the appropriate security code. When the receiver/controller receives such a digital signal, it compares the security code portion of the received signal against its stored security code, and, if a match is found, a controller portion of the receiver/controller outputs a signal to the proper system (e.g., the door lock actuators) of the vehicle for causing performance of the requested function (e.g., unlock door).
Portable transmitters of remote convenience systems transmit signals in the ultra-high frequency ("UHF") portion of the radio frequency ("RF") spectrum. Specifically, the frequency of the transmitted signals for such systems is in the portion of the RF spectrum that is allotted by the Federal Communications Commission ("FCC") for unlicensed transmission devices. FCC regulations stipulate that such unlicensed devices can not have a transmitted signal strength that exceeds a predetermined maximum value.
It is often desirable to accomplish remote control performance of certain functions at a longest possible distance. One example of such a function is the remote vehicle locator function. To illustrate such a scenario, consider a shopping mall patron exiting a shopping mall building and being faced with the task of locating their car within a vast shopping mall parking lot. It would be beneficial to be able to actuate the remote vehicle locator function from a location near the exit door of the shopping mall, before proceeding into the parking lot. Because of FCC regulations, an increase of transmitter power above the set limit is not possible.